Police dramatically launched a review into Nirvana lead singer Kurt Cobain's death on Thursday after new evidence was uncovered.

Four undeveloped rolls of film were found last month sealed in bags in a Seattle police photo lab nearly 20 years after his apparent suicide, cops revealed.

They said the scene was more clearer than earlier Polaroid photos and pledged to re-examine all the evidence in the case - but stopped short of launching a full reinvestigation yet.

The Smells Like Teen Spirit star was found dead in his home near Lake Washington by electrician Gary Smith on April 8, 1994, after he went to Cobain's home to do some work.

There he found the body of the singer. Police determined he died from a self-inflicted gun shot to the head. He was 27.

Seattle's chief medical examiner ruled Cobain had killed himself three days earlier - only days after he had left a rehab facility.

During the last years of his life, Cobain struggled with heroin addiction, illness and depression.

He also had difficulty coping with his fame and public image, and the professional and lifelong personal pressures surrounding himself and his wife, musician Courtney Love.

Speaking to a local TV station KIRO 7 at the time, Mr Smith said: "I noticed something on the floor and I thought it was a mannequin.

"So I looked a little closer and geez, that's a person. I looked a little closer and I could see blood and an ear and a weapon laying on his chest."

He added he had found a suspected suicide note atop planting soil in the greenhouse.

"I only read the bottom lines," he said "the bottom two lines said, 'I love you, I love you' to someone."

Before he was shot, police said Cobain had taken lethal dose of heroin.

Just weeks before his apparent suicide, police were called to his house after Cobain "locked himself in a room," and threatened to kill himself.

Cops were also told he "had a gun in the room."

The singer however reassured police he was not suicidal and didn't want to take his own life. However, police said after their investigation his death was clearly a suicide.

More than 7,000 mourners packed Seattle Center just two days after he was discovered for a public memorial, where a recording was played of Love, 49, reading Cobain's suicide note.

She also attended the memorial and gave some of his clothes to fans.

The new 35mm photos, which have a slight green tint due to the time spent undeveloped, were found alongside syringes Cobain had used and a drug kit inside the Seattle police evidence unit.

Police spokeswoman Renee Witt said officers plan to release the new photographs uncovered during the re-examination of the case and will answer questions on the anniversary of Cobain’s death next month.